The invention relates to improvements in apparatus for transmitting force between a rotary driving unit (such as the engine of a motor vehicle) and a rotary driven unit (such as the variable-speed transmission in the motor vehicle). In particular, the invention relates to a damper for a torque converter, in particular a damper with a two-piece plate configuration.
It is known to increase the torque capacity and durability of a damper for a torque converter by: increasing the thickness of components such as the flange and damper plates; increasing the distance between spring windows; improving window geometry; and changing the material of construction for components. The first option undesirably increases the weight, cost, and axial space requirements of the damper. Unfortunately, the second option can unfavorably limit the type of springs usable with the damper or the number of springs in the damper. The third option is focused primarily on the corners of the windows. It is known that greater stresses, which result in reduced strength and durability, are associated with the corners and that the smaller the radii for the corners, the greater the stresses will be. Therefore, the third option attempts to improve corner configuration. However, making corner radii larger can undesirably increase the overall size of the windows, or if the window sizes are not increased, undesirably reduce the size of the springs usable with the windows. Unfortunately, materials that result in greater durability are more costly; therefore, the fourth option undesirably increases the cost of the damper.
It is known to provide stops in a damper to prevent “over travel” of springs in the damper, for example, in response to overload torque received by the damper. The stops prevent the springs from fully compressing. Unfortunately, such stops are provided at the outer circumference of the damper, increasing the radial space required for the damper. Further, the torque received by the stops is transmitted through one or more plates in the damper with spring windows. As noted above, the torque capacity and durability of a damper plate is reduced at window corners. Therefore, transmitting the torque past the windows decreases the torque capacity of the damper or causes undesirable stress on the plates at the corners.
Thus, there is a long-felt need for a damper for a torque converter having increased torque capacity and durability without an increase in weight, size, or cost for the damper. There also is a long-felt need for a damper with stops that minimize torque transfer past spring window corners and that minimize radial space requirements.